(1) Field of the Invention
This invention generally relates to an oceanographic sensor suite wet well system, and more particularly to a device which provides an internal mounting of sensors in a dry pressure hull of a Large Diameter Unmanned Undersea Vehicle (LDUUV), the sensors accurately operating in a full pressure, free flood environment with circulating water.
(2) Description of the Prior Art
Existing underwater vehicle platforms with oceanographic equipment and sensors that operate in a flooded sea water environment traditionally mount the sensors in a large open flooded area or simply mount the sensors external to the vehicle envelope. The large flooded section in such a vehicle is usually a considerable volume which consists of massive pressure bulkheads and multiple feed-through penetrator lines. This large flooded volume reduces the overall buoyancy of the vehicle. Externally mounted sensors not only distort the hydrodynamic flow around the vehicle, causing increased noise and drag but also eliminate the capability of launching the vehicle through a launch tube.
There has been a need in the art in the area of LDUUV's to integrate oceanographic sensors into the water-tight pressure hull of the vehicle. These oceanographic sensors require exposure to a free flooded sea water environment, and the sensor suite requires the water to circulate at a minimum flow rate in order to ensure that the measured results are accurate. The LDUUV has no flooded hull sections and due to vehicle launch requirements, no equipment may be mounted external to the vehicle.
Known apparatuses for underwater sensing include the following:
U.S. Pat. No. 3,147,431 to Bennett et al. discloses an apparatus for measuring and recording the conductivity of sea water as a function of depth. The apparatus utilized to obtain these measurements includes a torpedo-shaped vehicle having a flooded forward compartment housing a depth-sensing element which moves a recording medium in one direction through a distance proportional to the hydrostatic pressure to which the element is subjected. An air-filled aft compartment of the vehicle contains a conductivity bridge circuit whose output drives an all-seeking servo system which rotates a recording stylus cooperating with the recording medium through an angle which is a function of the value of conductivity, the movement of the stylus being orthogonal to and in the same plane as the movement of the record medium, whereby the combined motion produces a trace of conductivity versus depth as the vehicle is lowered to the sea bottom and retrieved. The only measurement directly received is that of depth, and the device does not operate in a full pressure, free flood environment, with circulating water.
U.S. Pat. No. 3,762,214 to Bogusz discloses a system for monitoring contaminants in liquids in which there is a container open at one end, a plurality of sensors fixedly mounted within the container for sensing characteristics of the fluid and producing electrical signals, data recording means for receiving the electrical signals from the sensors, means within the container for periodically inducing oscillatory displacement of the fluid thereby cleaning the sensors, means for selective excitation of said means for inducing oscillatory displacement, and means for sequentially switching individual ones of said sensors and said data recording means. The system does not provide the capability of providing operation of sensors in a full pressure, free flood environment with circulating water, while maintaining that sensing system within a dry pressure hull. Instead, the sensors are continually and openly exposed to fluid via the opening 66, thereby also precluding selective detection which will occur in applicant's invention.
U.S. Pat. No. 3,824,852 to Otto discloses an electrically powered submerged pump, power circuit therefor, an oceanographic monitoring apparatus and method employing the same. Particularly, the submerged unit monitors water conditions by moving ambient water through a monitoring section for upper outlet passage 22 as shown in FIG. 1 thereof. As shown in Otto, there is provided a main water collecting chamber 16 and an upper float chamber 14, a sensory circuit block 84 being mounted within the float chamber 14 so as to be on a protected dry location. The block 84 is provided with a sensor 86 which projects into the stream of sample fluid passing through the passageway 22. The sensor 86 is connected to its associated block 84 by means of a wire passing through a sealed aperture in the wall 30. In the device of Otto, the pressure sensors per se are not mounted within the wet well as occurs in the present invention. Instead, four pumping chambers only are provided within the wet well or main water collecting chamber 16, whereas the sensors are entirely housed within a dry portion of the device and only include remote sensing elements which extend into the fluid passage 22 as shown in FIG. 1 thereof.
U.S. Pat. No. 4,287,763 to Richard discloses an apparatus for concentrating and sampling substances from sea water in which a relatively large measured volume of sea water is pumped through each of a series of in situ sampling chambers containing filtration, adsorption, absorption, or other retentive material.
The above devices are complicated in structure, tend to be difficult to use, and are, therefore, substantially unacceptable in solving the problem of integrating oceanographic sensors into the water-tight pressure hull of an unmanned undersea vehicle (UUV) such that the oceanographic sensors are exposed to a free flooded sea water environment with the water circulating at a minimum flow rate within the sensor suite in order to ensure accurate measured results.